The brightness of the synchrotron source makes it possible to collect high quality infrared spectra at spatial resolutions near the diffraction limit of the infrared light. Recently, we imaged the distribution of various chemical compounds in single living cells. Chemical mapping of nucleic acids, proteins, and lipids in single living mouse hybridoma B cells at a resolution of 3 ?m was performed. The main chemical classes (proteins, lipids, and nucleic acids) could be identified through the assignments of one or more vibrational bands with frequencies characteristic of their functional groups. In a single living hybridoma B cell, the Amide I, Amide II, and nucleic acid images showed a homogeneous distribution, with a maximum intensity in the center of the cell. In contrast, the aliphatic C-H group distribution departs markedly from that of the proteins. This functional group is mainly representative of the lipids. Interestingly, when cells at late stages of mitosis were analyzed, a high concentration of lipids was detected in the region where the contractile ring responsible for the cleavage furrow is located. This could correspond to the inward pulling of the lipids by the contractile ring occurring in that region just before cell division. After cell separation, the lipids again exhibited a heterogeneous distribution resembling the one observed in a single isolated cell.